Here's a simple holder for filament spools which uses PVC pipes.
The design's intent is to allow for easy changing of spools without having to undo fittings/connectors. Simply pull the horizontal pipe up and switch out your filament.
This design consists of two different PVC pipe fittings: a top and bottom.
The top is screwed to one end of the pipe and the bottom is screwed to the pipe and the mounting surface.
In the SCAD file you can freely change any/all of the dimensions to fit your needs and materials.
NOTE: specify the model to generate in the SCAD file.
I printed a set of these (2 tops and 2 bottoms) in ABS and it's working great. I covered it with a plastic storage box to keep my two cats away from it.
I printed with 3mm ABS and this thing came out strong!
Printing with a 3 or 4 mm brim/hat helps adhere the bottom piece to the print bed.
Also, sliced with Slic3r.